Laser types and power

Do You Need a MOPA Fiber Laser to Put Color on Metal?

Published · By the Laser Lineup editors

Summary

Not to get color at all. xTool says its standard-fiber F1 Ultra can color-engrave stainless steel and titanium. What MOPA adds is separate control over pulse width and pulse frequency, which gives you more room to tune colors and fine detail. For logos and serial numbers, a standard fiber laser does the job.

Where the color comes from

Color on stainless steel is a thin oxide layer grown by the laser's heat. Different thicknesses show up as different colors through light interference. xTool describes its MOPA-equipped F2 Ultra (60W MOPA plus a 40W blue diode) as adjustable from 2 to 500 ns and 30 to 4,000 kHz, and says it gives superior color results on metal. The F1 Ultra gets color on stainless and titanium without MOPA. The difference is how far you can steer the result.

What pulse control changes

Most fiber marking lasers fire short pulses instead of a continuous beam. MOPA stands for Master Oscillator Power Amplifier: one stage creates the pulse and a second stage amplifies it. JPT, a laser-source maker, lists its M8 MOPA lasers with pulse widths of 1 to 350 ns and repetition rates of 1 to 4,000 kHz, each adjustable on its own.

xTool's parameter guide explains the effect. Lower the frequency and both peak power and energy per pulse go up. Widen the pulse and peak power drops while pulse energy stays the same. High peak power is used for fine engraving, high pulse energy for cutting metal and removing rust. The F1 Ultra's settings include frequency but have no pulse-width control.

Sources

  1. JPT Opto-Electronics — M8 MOPA Fiber Laser 20–50W
  2. xTool Support — Processing Parameters for xTool F2 Ultra
  3. xTool Support — xTool F2 Ultra Q&A
  4. xTool Support — xTool F1 Ultra Q&A
  5. xTool Support — The Processing Parameters for xTool F1 Ultra

Specs and prices are as published on these pages on the date above and can change; check the manufacturer or retailer before you buy.

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